This invention relates to a folding machine for folding sheets. Such a machine is particularly suitable for use in a laundry, where it may be located to fold flatwork articles such as sheets, tablecloths, pillow cases and the like which issue from an ironing machine. For ease of explanation the term "sheet" will be used herein throughout to refer to such an article. However, the scope of the invention is not intended to be restricted to sheets per se.
It is customary when processing a sheet in a laundry to iron it in, for example, a calendar ironer, whence it passes to a folding machine.
In practice, two folding machines are generally used, namely a primary folder which makes two transverse folds across the length of the sheet and a cross-folder which makes two or three folds at right angles to the primary folds.
The present invention is concerned with a primary folder of a type wherein sheets are folded at a desired fold line by tucking the fold line between contra-rotating rollers or conveyors.
Usually folders of this type measure the sheet to find its length and then they fold the sheet in half and in half again. To do this they generally require a sensor located on an input conveyor of the folder at least as far in front of the fold mechanism as half the length of the longest sheet to be folded. Thus folders of this type tend to be long.
Such a long machine can be inconvenient to the amount of space it occupies. In addition the length of such a machine, which is adapted to fold long sheets, may necessitate the incorporation of a memory in the machine. This memory is required to enable the machine to differentiate between short sheets which follow each other closely through the machine.
The present invention seeks to provide an improved primary folding machine. According to one aspect of the invention there is provided a folding machine for folding sheets comprising a first sheet conveyor; a second sheet conveyor; drive means for the second conveyor capable of driving the second conveyor forwardly in the same direction as the first conveyor, stopping the second conveyor movement to give a pause, and driving the second conveyor in reverse; a fold gap between the the conveyors; a bridging mechanism for controllably bridging the fold gap; a fold mechanism beneath the fold gap; and a measuring device for measuring sheets fed on to the first conveyor. The measuring device is effective to determine and control the times at which the bridging mechanism is operated, the second conveyor pauses and reverses, and the fold mechanism operates.
According to another aspect of the invention there is provided a method of folding a sheet, firstly in half at its midpoint and secondly in half again at its quarter and three-quarter points. The method includes the steps of feeding the sheet from a first conveyor across a fold gap on to a second conveyor; arresting the movement of the second conveyor for a determined pause time, a loop being formed in the sheet beneath the fold gap at the pause and at the reverse of the second conveyor; and tucking the doubled sheet of the loop into a fold mechanism at the quarter and three-quarter points of the sheet.
The provision of a pause in the movement of the second conveyor before reversal allows a long sheet to be fed into a loop beneath the fold gap. The arrangement allows the over-all length of the machine and the measuring station to be relatively short, even for long sheets. The length of the pause necessary will depend upon the length of the sheet. For sheets below a certain length there will be no pause and reversal of the second conveyor will be immediate.